Abnormalities in the brain may make some people more likely to become drug addicts, according to scientists at the University of Cambridge. They found the same differences in the brains of addicts and their non-addicted brothers and sisters.

The study, published in the journal Science, suggested addiction is in part a “disorder of the brain”. Other experts said the non-addicted siblings offered hope of new ways of teaching addicts “self-control”. It has long been established that the brains of drug addicts have some differences to other people, but explaining that finding has been more difficult. Experts were unsure whether drugs changed the wiring of the brain or if drug addicts’ brains were wired differently in the first place.

Lead researcher Dr Karen Ersche said: “It has long been known that not everyone who takes drugs becomes addicted. It shows that drug addiction is not a choice of lifestyle, it is a disorder of the brain and we need to recognise this.”

Dr Paul Keedwell, a consultant psychiatrist at Cardiff University, said: “Addiction, like most psychiatric disorders, is the product of nature and nurture. We need to follow up people over time to quantify the relative risk of nature versus nurture. If we could get a handle on what makes unaffected relatives of addicts so resilient we might be able to prevent a lot of addiction from taking hold.”